Stopping childhood obesity before it begins
Do you ever get the feeling that by the time you measure BMI in a 2-year-old, you have already lost the battle in preventing the child from becoming overweight or even obese? I certainly do. Based on CDC growth charts, age 2 is the first time BMI is measured and evaluated, but children this age have already been seen at least nine times for well-child visits alone. These visits present clinicians with an opportunity to influence feeding behaviors early in life and quite possibly prevent obesity from developing.
It is well known that childhood obesity is a growing problem nationwide, and numerous epidemiologic studies verify what clinicians see in their practices. One survey showed that from 1999 to 2002, 10.3% of all children aged 2-5 years had a BMI in the 95th percentile or higher. All ethnic groups are afflicted (the proportion of white youngsters in this category was 8.6%, blacks 8.8%, and Mexican Americans 13.1%). It is also known that compared with other babies, the chances these “big babies” will become big children, adolescents, and adults are higher.
The first opportunity for prevention Promoting breastfeeding is one of the most important things a clinician who interacts with pregnant patients (or women planning to get pregnant) can do.
Studies show that breastfeeding is associated with a decreased prevalence of heaviness in childhood, adolescence, and adulthood. In fact, a recent meta-analysis strongly supported a dose-dependent relationship between duration of exclusive breastfeeding and lower risk of becoming overweight. The American Academy of Pediatrics (AAP) and the American Dietetic Association recommend breastfeeding for at least the first six months of a baby's life and preferably for the first year. In contrast, formula feeding has been associated with an increased risk of becoming overweight and developing health problems.
Growth and development are assessed as early as the first newborn checkup, and additional measurements are taken when the baby presents with acute illness. All these measurements can be plotted on the height and length growth charts to determine in what percentile the child's growth lies. Head circumference is also measured in children younger than age 2 years.
But how often do we plot on the weight-for-length chart as well? This can be revealing. For example, Misty is a 1-year-old girl who weighs 24 lb (90th percentile) and is 28.5 inches in length (25th percentile); her weight-for-length, however, is >95th percentile.
The WHO alternative measurement
There is an alternative to the CDC charts for identifying overweight and obese infants and children beginning at birth. The World Health Organization (WHO) growth charts (published in 2006) differ from the CDC's version in that they allow earlier assessment of BMI and are not based on the average weights or heights for a population. The WHO growth curves from birth to 2 years of age are based on infants who were exclusively or predominantly breastfed for at least 12 months, establishing a new criterion that uses the breastfed infant as the standard for measuring growth. In short, the new standards provide assessment based on how a child should grow. According to one investigator, if the WHO growth charts were adopted in place of the CDC charts, fewer than 5% of U.S. infants would be below the 5th percentile for weight, and more U.S. infants would be above the 95th percentile. These charts are available on the Internet (www.who .int/nutrition/media_page. Accessed March 7, 2008).
Another difference in the WHO standards is that they are presented as z scores or SD scores, with 0 as the mean (right side of graph, Figure 1). For example, height is a measurement that follows a normal (or bell-shaped) distribution. However, weight and BMI may have abnormal distributions. This explains why the space between the lines that signify 2 and 3 SDs from the mean varies. Using the BMI standards from the WHO, a z score of 2-3 is considered overweight and a z score >3 is considered obese. Using Misty's example, her BMI would be calculated as 20.8. When plotted on the WHO BMI-for-age girls' chart, her z score is between 2 and 3, which identifies her as overweight.
In support of improving identification of children who are overweight, the American Medical Association recently released recommendations to standardize at least the terminology used for children to match the WHO and adult criteria so that: 85th-94th percentile is classified as overweight (not “at risk for overweight,” as previously) and >95th percentile is classified as obese (not “overweight”).
How to begin a discussion
What if an infant is identified as overweight or obese? Is it too soon to bring up the topic of weight with the parents? The AAP Policy Statement on Prevention of Pediatric Overweight and Obesity states “at any age, an excessive rate of weight gain relative to linear growth should be recognized and underlying predisposing factors should be addressed with parents and other caregivers.” Evidence shows that monitoring, prevention, and intervention at a very early stage would be more effective than waiting until the problem is well established.
Some pediatricians have expressed concern over whether it is appropriate to use the terms “overweight” and “obese” in reference to children. If the child is diagnosed with obesity, clinicians worry he or she may feel labeled and parents will feel guilty. There are also the popular misconceptions that a “fat” baby is healthy and that “baby fat” will disappear over time.
No official recommendations exist regarding terms to use when broaching the subject with parents. However, clinicians should get the point across that the infant or child is not at the healthiest weight for his height, which opens the door to other possible health risks in the future if the problem continues. Let the parents know that the child's weight is an important concern to you as his or her health-care provider. At this point, asking the mother if she agrees there is a problem and if it is important to her is one of the first steps in assessing readiness to change behaviors.
At one of the earlier well-child visits, providing all parents with information on healthy feeding habits may also help with prevention of overfeeding. In my own practice, I have developed one handout for parents of infants (Table 1) and another for toddlers and preschoolers. The information in the handout can also be used as goals for behavior change.
Follow-up questions for the parent
If the parent recognizes that the infant or child is heavier than is healthy, request permission to ask some questions to understand the factors contributing to the problem. At this point it is advisable to take a diet and activity history. There are great examples of these for each age group in the AAP's Bright Futures health-promotion publications (www.brightfutures .org). It is also important to assess if a parent is interpreting the infant's behaviors or cues accurately. A question like “How does your infant let you know he or she is hungry?” or “How does your infant let you know he or she is full?” may help you identify misinterpretations. Allowing infants to develop feeding self-control is an important developmental task.
This discussion will probably give you a good idea about factors contributing to the problem, but ask the parent first if any such factors have been identified. Interventions will be more successful if they are geared toward an issue that the parent has identified as a contributing cause, even if you do not consider it the most important one. Do not jump in immediately with your advice. Instead, ask the parent “What do you think you can do to help your child with this problem?” If the parent cannot come up with anything, offer your suggestions.
Work together with the parent to identify potential barriers and what might be achievable small goals. “Case study: Justine” (at left) provides an example of how this advice can be put into practice.
Ms. Waldrop is associate professor of pediatrics in the School of Medicine at the University of North Carolina in Chapel Hill, where she is also a clinical assistant professor in the School of Nursing.
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